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Concept: Piriformis muscle

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OBJECTIVE: To present a group of anatomical findings that may have clinical significance. DESIGN: This study is an anatomical case report of combined lumbo-pelvic peripheral nerve and muscular variants. Setting: University anatomy laboratory. Participants: One cadaveric specimen. METHODS: During routine cadaveric dissection for a graduate teaching program, unilateral femoral and bilateral sciatic nerve variants were observed in relation to the iliacus and piriformis muscle, respectively. Further dissection of both the femoral nerve and accessory slip of iliacus muscle was performed to fully expose their anatomy. RESULTS: Piercing of the femoral nerve by an accessory iliacus muscle combined with wide variations in sciatic nerve and piriformis muscle presentations may have clinical significance. CONCLUSIONS: Combined femoral and sciatic nerve variants should be considered when treatment for a lumbar disc herniation is refractory to care despite positive orthopedic testing.

Concepts: Spinal disc herniation, Biology, Muscle, Sciatic nerve, Sciatica, Lumbar plexus, Dissection, Piriformis muscle

27

Piriformis syndrome is an uncommon cause of sciatica. It is frequently posttraumatic or in relation with anatomic abnormalities; its diagnosis is often difficult, and it needs the exclusion of common causes of sciatica. Piriformis syndrome caused by drug-induced myopathy in relation with use of statin has not been described before. We report the case of a 60-year-old woman with a history of dyslipidemia treated by atorvastatin since 3 years, who complained of a chronic pain in the left buttock radiating to the posterior thigh and knee that had been increasing during the previous 3 months. At physical examination, the patient has lameness at walking. The lumbar spine was not tender and had full range of motion. Findings on all radicular provocation tests were normal, and tests stretching the piriformis muscle were positive. Radiographs of the pelvis and lumbar spine were unremarkable. Magnetic resonance images of the lumbar spine and pelvis was performed, showing high signal intensity in T2-weighted sequences of the piriformis muscle. Treatment with atorvastatin was occasionally discontinued, and the patient reports an improvement of the sciatic pain. Reintroduction of atorvastatin was associated with relapse of the sciatic pain. Thus, clinical features and magnetic resonance imaging findings confirm that sciatic pain was related with piriformis myopathy as an adverse effect of statin.

Concepts: Spinal disc herniation, Causality, Magnetic resonance imaging, Sciatic nerve, Sciatica, Pelvis, Piriformis muscle, Piriformis syndrome

3

Pain that extends from the buttock down the course of the sciatic nerve is common. Nearly 85% of cases are associated with a disk disorder. The causes, assessment, and management of sciatica are discussed.

Concepts: Spinal disc herniation, Sciatic nerve, Sciatica, Piriformis muscle

2

Piriformis syndrome is a nondiscogenic cause of sciatica from compression of the sciatic nerve through or around the piriformis muscle. Patients typically have sciatica, buttocks pain, and worse pain with sitting. They usually have normal neurological examination results and negative straight leg raising test results. Flexion, adduction, and internal rotation of the hip, Freiberg sign, Pace sign, and direct palpation of the piriformis cause pain and may reproduce symptoms. Imaging and neurodiagnostic studies are typically normal and are used to rule out other etiologies for sciatica. Conservative treatment, including medication and physiotherapy, is usually helpful for the majority of patients. For recalcitrant cases, corticosteroid and botulinum toxin injections may be attempted. Ultrasound and other imaging modalities likely improve accuracy of injections. Piriformis tenotomy and decompression of the sciatic nerve can be done for those who do not respond.

Concepts: Spinal disc herniation, Neurology, Sciatic nerve, Sciatica, Pelvis, Botulinum toxin, Piriformis muscle, Piriformis syndrome

2

The purpose of this study was to determine the diagnostic accuracy of the straight leg raise (SLR), active piriformis, and seated piriformis stretch tests in identifying individuals with sciatic nerve entrapment.

Concepts: Spinal disc herniation, Sciatic nerve, Sciatica, Straight leg raise, Piriformis muscle

0

Sciatica is a highly prevalent cause of morbidity, commonly resulting from intra-spinal pathological processes. Many cases can have extra-spinal etiologies and can be clinically challenging. Certain scenarios should suggest an extra-spinal etiology, particularly total and revision hip arthroplasty, surgical hip dislocation, hip arthroscopy, and surgery in the lithotomy position. We review the post-operative clinical scenarios where sciatic neuropathy may occur, along with the pertinent imaging findings.

Concepts: Medicine, Spinal disc herniation, Sciatic nerve, Sciatica, Hip replacement, Piriformis muscle

0

A middle rectal artery arising from the lateral sacral artery (MRAls) in the right pelvis of a 99-year-old male was observed. Although variations of the origin of the middle rectal artery have been reported on many occasions, there are few descriptions of the trajectory in the literature. In our case, the MRAls branched from the lateral sacral artery on the sacral surface close to the third sacral sympathetic ganglion and immediately penetrated the third sacral splanchnic nerve and the parasympathetic pelvic splanchnic nerve from the ventral ramus of the forth sacral nerve. The MRAls entered in the lateral wall of the rectal ampulla without giving off a prostatic branch. Preservation of the pelvic autonomic nerves are crucial in rectal cancer excision to preserve the autonomic functions. The close topography of the MRAls to the origin of the fine autonomic nerves should be noted.

Concepts: Nervous system, Autonomic nervous system, Rectum, Parasympathetic nervous system, Internal iliac artery, Piriformis muscle, Middle rectal artery, Superior rectal artery

0

To conduct radiologic anatomical study on the relation between S1 sacroiliac screws' entry points and the route of the pelvic outer superior gluteal artery branches with the aim to provide the anatomical basis and technical reference for the avoidance of damage to the superior gluteal artery during the horizontal sacroiliac screw placement.

Concepts: Gluteus maximus muscle, Piriformis muscle

0

Objective: To observe the possibility of posterior approach via sacrectomy for reaching intrapelvic sacral plexus and expose the deep intrapelvic origin of sciatic nerve from sacral plexus in order to perform nerve graft. Methods: Five adult cadaver specimens were used in the study with prone position in May 2012. Cut off the gluteus maximus along the origins and lift to the lateral side, the piriformis was lay beneath. The sciatic nerve and the inferior gluteal nerve pierced from the infrapiriformis foramen in the operative field. Excise the origin of the piriformis via sacrectomy with osteotome and the length and width of the insertion on sacrum were measured. The piriformis was resected and then the sacral nerve roots beneath were exposed. The S2-S4 sacral nerve roots and the deep intrapelvic origin of sciatic nerve from sacral plexus were revealed after carefully dissecting. From July 2012 to June 2016, nine patients with lumbosacral plexus injury were performed surgery through the posterior approach in Department of Hand Surgery, Beijing Jishuitan Hospital.There were 6 male and 3 female patients, with a mean age of 29 years. All patients were diagnosed as upper and lower sacral plexus injury, in one of them combing with contralateral lower sacral plexus injury. The average time from injury to operation was 8.3 months. Results: The length and width of the piriformis insertion on sacrum were (3.44±0.15) cm and (2.42±0.11) cm, respectively. The deep intrapelvic origin of sciatic nerve from sacral plexus in all nine patients can be revealed clearly and there was enough operative space that nerve transfer or graft can be performed through the posterior approach via sacrectomy. The total blood loss during operation was (1 822±1 523) ml. Conclusion: The piriformis and part of sacrum it attached can be resected safely through the posterior approach and the deep intrapelvic sacral plexus and the origin of sciatic nerve can be well exposed.

Concepts: Sciatic nerve, Sciatica, Anatomy, Height, Nerves of the lower limb and lower torso, Inferior gluteal artery, Piriformis muscle, Sacral plexus

0

Distinct calcific tendonitis associated with chronic pain refractory to conservative treatment can require operative treatment. Symptomatic calcific tendonitis of the piriform muscle, despite calcific tendonitis of other regions, is an extremely rare diagnosis. We report about a young athlete with persistent gluteal pain despite long-term conservative treatment. MRI scans revealed tendonitis calcarea with surrounding soft tissue inflammation. On open surgical removal of the calcification, pain symptoms were relieved and the patient was able to return to sports.

Concepts: Inflammation, Sciatica, Pelvis, Soft tissue, Piriformis muscle